Generally the battery life of an electronic timepiece is more than one year. If the battery is changed on each anniversary, a portion of its useful life is sacrificed. If on the other hand, it is sought to make use of the battery for its full life, the fact that the battery is depleted does not become obvious until the timepiece stops. This causes loss of time and general inconvenience. It is preferable to change the battery near the end of its useful life but during normal operation of the electronic timepiece.
As a means for indicating that the battery is becoming exhausted, it has been proposed to provide a signal light or to cause flashing of the time display. However, these means have not been found to be satisfactory to the user.